Endocardium

Endocardium

Infobox Anatomy
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The endocardium is the innermost layer of tissue that lines the chambers of the heart. Its cells, embryologically and biologically, are similar to the endothelial cells that line blood vessels.

The "endocardium" overlies the much more voluminous myocardium, the muscular tissue responsible for the contraction of the heart. The outer layer of the heart is termed epicardium and the heart is surrounded by a small amount of fluid enclosed by a fibrous sac called the pericardium.

Function

Recently, it has become evident that the endocardium, which is primarily made up of endothelial cells, controls myocardial function. This modulating role is separate from the homeometric and heterometric regulatory mechanisms that control myocardial contractility. Moreover, the endothelium of the myocardial (heart muscle) capillaries, which is also closely appositioned to the cardiomyocytes (heart muscle cells) are involved in this modulatory role. Thus, the cardiac endothelium (both the endocardial endothelium and the endothelium of the myocardial capillaries) controls the development of the heart in the embryo as well as in the adult, for example during hypertrophy. Additionally, the contractility and electrophysiological environment of the cardiomyocyte are regulated by the cardiac endothelium.

The endocardial endothelium may also act as a kind of blood-heart barrier (analogous to the blood-brain barrier), thus controlling the ionic composition of the extracellular fluid in which the cardiomyocytes bathe.

Role in disease

In myocardial infarction, ischemia of the myocardium can extend to the endocardium, disrupting the inner lining of the heart ("Transmural" infarction). Less extensive infarctions are often "subendocardial" and do not affect the endocardium. Subendocardial infarction's are much more dangerous than Transmural infarctions because they create an area of dead tissue surrounded by a boundary region of damaged myocytes. This damaged region will conduct impulses more slowly, resulting in irregular rhythms. The damaged region may enlarge or extend and become more life-threatening. During Depolarization the impulse is carried from endocardium to epicardium, and during Repolarization the impules moves from epicardium to endocardium.In infective endocarditis, the "endocardium" (especially the endocardium lining the heart valves) is affected by bacteria.

External links

* - "Heart and AV valve" (atrial endocardium)
* - "Heart and AV valve" (ventricular endocardium)


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Look at other dictionaries:

  • Endocardium — En do*car di*um, n. [NL., fr. Gr. e ndon within + kardi a heart.] (Anat.) The membrane lining the cavities of the heart. [1913 Webster] …   The Collaborative International Dictionary of English

  • Endocardĭum — (griech.), die innerste Herzhaut, s. Herz …   Meyers Großes Konversations-Lexikon

  • Endocardium — vgl. Endokard …   Das Wörterbuch medizinischer Fachausdrücke

  • endocardium — [en΄dō kär′dē əm] n. [ModL < ENDO + Gr kardia, HEART] the thin endothelial membrane lining the cavities of the heart …   English World dictionary

  • Endocardium — The lining of the interior surface of the heart chambers. The endocardium consists of a layer of endothelial cells and an underlying layer of connective tissue. * * * The innermost tunic of the heart, which includes endothelium and subendothelial …   Medical dictionary

  • Endocardium — En|do|car|di|um das; s, ...dia <aus nlat. endocardium »Herzinnenhaut« zu ↑endo... u. gr. kardía »Herz«> svw. ↑Endokard …   Das große Fremdwörterbuch

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  • Endocardium — vidinis širdies dangalas statusas T sritis gyvūnų anatomija, gyvūnų morfologija atitikmenys: lot. Endocardium ryšiai: platesnis terminas – širdis sinonimas – endokardas …   Veterinarinės anatomijos, histologijos ir embriologijos terminai

  • Endocardium — endokardas statusas T sritis histologija atitikmenys: lot. Endocardium ryšiai: platesnis terminas – širdis siauresnis terminas – endotelis siauresnis terminas – poendotelinis sluoksnis siauresnis terminas – raumeninis elastinis sluoksnis …   Medicininės histologijos ir embriologijos vardynas

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